Automatic choke for shot guns



Nov. 27, 1956 w. T. ROCHELLE 2,771,698

AUTOMA'IIC CHOKE FOR SHOT GUNS yFiled Dec. 4, 1953 INVENTOR.

MlzamHocheNe BY @am Ld .GBM/vw Hornz] tent C@ 2,771,698 Y Patented Nev. a?, rase AUTMATIC CHKE FOR SHOT GUNS William T. Rochelle, Atlanta, Ga. Application December 4, 1953, Serial No. 396,155

4 Claims. (Cl. 42-79) This invention relates to shot guns and has particular relation to an automatic choking device for the muzzles of such guns.

In the use 1of shot mins and particularly those of the automatic type, it has been found that when Ithe iirst shot is fired against a close target, the cone of dispersion is suiciently narrow to give a suiciently large pattern to hit the target without its being too greatly damaged. At a grea-ter distance, for a second shot, with the target naturally farther away, a narrower cone of dispersion may 'be employed to produce the same size pattern and thus with the same kind of shell Iand accurate shooting, the same result may be produced. In addition, the production of the small pattern at the greater ranges, produces less wounded birds. To produce these dilferent sized di-s` persion cones, the variable choking mechanisms are provided.

The primary object of this invention is the provision of an improved variable automatic choke for shot guns.

Another object of the invention is the provision of an improved choke which will -be automatic in its operation with a plurality of successive discharges of the gun.

Another object of the invention is the provision of an improved choke for shot guns wherein with the rotary movement of one part with relation to another, the diameter of the choke will be made smaller.

Still another object of the invention is the provision of a choke wherein a threaded connection between two members is utilized to cause the slitted ends of a bore to move closer together to make the diameter smaller.

A-still further object of the invention is the provision of an improved choke vfor shot guns wherein the gas pressure from the discharge of the gun is utilized to provide power to cause constriction of the -opening of the muzzle of the gun.

Another and further yobject of the invention is the provision of an -automatic choke mechanism wherein gas pressure from the discharge of the gun causes the rotation of relatively rotatable members, Iwhich in turn causes the coaction between .a ring contacting with a conical surface, to constrict slitted portions to decrease the diameter of the choke.

Another and still further object of the invention is the provision of an automatic choke mechanism wherein a gas duct member receives the I`gas pressure from the bore yand `transmits it to a tangentially located abutment on a rotary member lwhich latter operates to coact to constrict the diameter of the bore to increase the choke thereof.

Still another and further object of the invention is the provision of an improved choke mechanism having a pivoted duct member having one end of its duct connected to the bore and the other end ybent to discharge substantially in a plane normal to the -aXis of the -bore and in a tangential direction relative to a -rotary member coacting with the slitted ends of the bore lto constrict the latter when the rotary member is rotated by 4the blast of gas from the bore as the gun is discharged.

Other and further objects of the invention will be apparent to those skilled in the art -from a reading of the complete specification.

Referring to the drawing wherein is illustrated anembodiment of the invention.

Fig. 1 is aside elevation of the invention when attached to the muzzle of a shot gun.

Fig. 2 is a longitudinal cross section of the structure shown in Fig. 1.

Fig. 3 is a View `oit the structure shown in Fig. l as viewed from the left from the line 3-13.

Fig. 4 is a cross sectional view on the line 4-4 of Fig.2.

Fig. 5 is a view from ythe line 5 5 of Fig. l.

Fig. 6 is a detail view on the line 6 6 of Fig. l.

Similar reference characters refer to the same or similar parts throughout the specification and drawing.

Y The reference character 10 designates the' shot gun barrel -to which the automatic choke mechanism is attached. The end of the barrel is provided with means for retaining the chokemechanism in place as the threaded portion 10a.

To the threaded portion 10a is secured a similar and coacting linteriorly threaded portion 1 1a of the main body 111 of the choke mechanism. This main body member` l-is an elongated member having an extended porti-on at the inner end whichfits snugly the outside of the muzzle of Ithe gun barrel 10 and providing stability for the choke mechanism when the Egun is discharged. The main body member-l1 is provided with a slot 1lb and a screw l2 is threaded into the body mem-ber 11 across the slot'lb to provide a tightening mean-s to cause the main -body member to grip the gun barrel 10 and preventrelative movement after the two have -been adjusted to their proper relative positions.

Threaded in the end of the threaded portion 11a at the forward end is the slitted boremember 13 of' the choke mechanism which has exterior threads l3nt which cooperate with the forwardportion ofl the interior threads 11a as already pointed out. At the'forward end of the slitted bore member ll3k are slits forming the slitted sec-V tions 13b which because of the slits are flexible in order to permit the varying of the diameter .of the choke. it is to be here noted that the interior of the bore of the slitted bore member at the choke end may be made the same diameter as the remainder of its length or it may be made smaller to give an initial choke, at the option ofr the maker and depending upon the result desired. In either construction, the interior diameter will become smaller asthe` gun is successively discharged, as will be Y later explained. v

The forward portion of the slitted bore member'13 is provided with exterior threads -13c upon which is mounted the threaded portion 14a of the` cylindrical member 14.

This cylindrical member i4 is provided with a surfacel at its forward end as at 1417 which resembles the inside of a ring. it is to be noted that the outer surface of` the slitted bore member 13 is provided with an outwardly tapering surface 13d which coacts with the ring-shaped surface 14b so that when the cylindrical member 13 is moved to the rear relative to the slitted bore member 13, the flexible ends 13b. will be broughtcloser to the axis of the bore and the choke will be Vof smaller diameter. When the outer cylindrical member 14 is turned on the thread 13e, it is believed to be obvious that it will move axially and in an axial direction which will depend upon which way it is given rotary movement. lt is to be noted that there is sufficient clearance between the outer end of that portion of the main body member 11 which surrounds the end of the slitted member i3 and the rear end of the outer cylindrical member 14 to permit the latter to have suicient backward movement to close the choke to the desired degree.

The main body member 11 is provided with a chamber llc in which is located the duct member 15. The duct member 15 has at its rearward end a ball-shaped portion 15a and at its forward end a bend which ends in an angular portion 15b.

A duct 15a` extends from the ball-shaped portion 15a through to the opposite end to the opening on the end of the angular portion 15b.

The rear opening of the duct 15c registers with an opening 16 which is here shown, though not necessarily, as being at the edge of the inner end of the slitted member 13. It is clear from this construction that when the gun is discharged, the gas pressure from the bore will enter the duct 15c from the opening 16. Referring particularly to Figs. 3 and 4 it will be noted that the angular portion 15b is at such an angular position that it is pointed substantially at the periphery of the outer surfacel of the outer cylindrical member 14.

Spaced around the periphery of the outer cylindrical member 14 are the notches 14e at a distance apart and at such points as to produce the desired movement of the outer cylindrical member about its axis so as to bring about the desired constriction of the slitted portion 13b at successive discharges of the gun in a manner to be described. The length of the angular portion 15b of the duct member 15 is such that the end of the angular portion 15b is normally within the notch 14C with the opening of the duct 15.'.` adjacent one of the walls or abutments of one of the notches 14e. In order to hold the end of the angular portion 15b Within the notch 14e until the gun is discharged and then to permit it to retract to allow the outer cylindrical member to partially rotate, there is provided a spring member 17 situated in a recess 11d.

This recess lid and the bottom of the chamber 11c are of such dimensions that when the gun is discharged, the ball portion 15a of the duct member 15 will slightly swivel in its socket 11e and the outer end angular portion V15b will move downwardly to permit the outer cylindrical member 14 to partially rotate under the inuence of the gas as it imninges against the wall or abutment of the notch 14e with which it is in register.

But since the rotation of the outer cylindrical member 14 causes a movement axially relative to the slitted member 13.- due to the coaction of the threads on the outer cylindrical member and the slitted member 13, it follows that there will be a further coaction between the ringshaped contacting surface 14b and the outer tapered surface of the slitted portions 13b. This causes the constriction ofthe slitted end portion 13b with the resultant decrease in the diameter of the choke. When a successive notch 14e and its abutment cornes to register with the angular portion 15b, the outer cylindrical member comes to rest. In the present embodiment of the invention, there are shown three notches 14` which make possible a corresponding number of changes in the diameter of the choke as the gun is successively discharged. This number is not, however, mandatory.

To assist the outer cylindrical member 14 to come to rest in position for a further rotary movement when the gun is again discharged, there is provided a spring detent member 18 which is located within the slot 14x in the outer periphery of the outer cylindrical member 14 and is secured in place by a screw 19. This detent member 18 has a turned-down end 18a which is in position to engage notches 13d in the threaded surface 13C. There are a number of notches 13d similar to the number of notches 14e and they are similarly spaced so that when a notch 14C has the end of the angular portion 15b in register therewith, the turned-down end 18a will engage a Vcorresponding notch 13d.

Having described the construction of the several parts, the description of the installation and operation of the invention as a whole will now be made.

In preparation for the installationy of the automatic A 4 choke mechanism, the outer end of the gun barrel is threaded with the thread a to a suflcient distance to receive the threads 11a of the main body portion 11. The screw 12 is now tightened. The slitted member 13 is now threaded into the main body member 11 without the duct member being in its place. After removal the slitted member 13 is then provided with a hole or opening 16 at a place which when returned to position will bring the opening 16 in registry with the opening in the duct member 15 through the `ball end 15a.

Now with the duct member 15 and its spring member 17 in their places, the slitted member 13 is replaced within the main body member 11. The outer cylindrical memer is now screwed in place to a point where the notch 14c shown at the left side in Fig. 4, is in position to be in registry with the angular end 15b of the duct member 15. lt is to be understood that when this is done, the spring detent end 18a will be in registry with one of the notches 13a. As already pointed out, the choke, with the parts so adjusted, will be at the largest diameter used but with the ring-shaped surface 14b in position to act on the.

tapered surface of the outer end of the slitted members 13b to force the latter toward the axis of the bore as soon as further rotary movement of the outer cylindrical member takes place. The gun is now ready for use.

When the gun is discharged, presumably at a bird which is near the gun, the choke being at normal position will give a normal discharge and the discharge will give a normal dispersion cone and pattern. As the charge passes the opening 16, part of the gas pressure passes through the opening 16 and into the opening of the duct 15a` within the member 15. As the gas passes through the duct 15C and out of the opening at the opposite outer end, it impinges against the wall or abutment of the notch 14C in the outer cylindrical member 14. Since this pressure is substantially tangential to the outer cylindrical member 14, the latter will be turned. In starting this turning movement, the turned-down end 18a is forced from its small depression or notch 13d and follows the thread until another depression or notch 13d arrests the turned-down end 18a, and stops the rotation of the outer cylindrical member 14. At the same time, the angular portion 15b compresses the spring 17 and moves out of the notch 14C.

As soon as the outer cylindrical member 14 moves as just described, the threads coacting with each other cause the outer cylindrical member to move as a whole in an axial direction toward the rear of the gun. This brings into action the ring-shaped surface 14b with its pressing action on the outer tapered surface of the outer end of the slitted end section 13b with the result that the inner diameter of the bore, at the outer end, is made` smaller and acts as a greater choke than when the iirst discharge took place.

By the time this has taken place, the bird or other target, if not hit, will be farther away and the next smaller size choke will be automatically ready for the next discharge. As this next discharge takes place, another partial rotary movement takes place and other notches 13d and 14a` will be brought into registry with the turned-down end 18a and the angular portion 15b respectively, as already described. When the gun is discharged,V

the same cycle takes place with result that a further choke effect is obtained. The same routine is followed until the choke is to its smallest diameter or the target is hit.

To prepare for another shooting, the rotation of the outer cylindrical member 14 is reversed by hand untilv the rst notch 14c is in registry with the angular portion. 15b f of the duct member 15. The gun and automatic choke mechanism are now ready for another target.

While there has been illustrated and described on modication of this invention, it is to be fully understood that the disclosure is merely illustrative and that modi.

cations and changes may be made without departing from the spirit of the invention and within its scope as claimed.

Having described my invention, what I claim is:

1. An automatic choke for gun barrels comprising a bore member having a bore, means for securing the bore member to the barrel of a gun with the bore in axial alignment with the gun bore, the bore member having 5 slits at the outer end of the bore, an outer cylindrical member having a gas-impinging surface and surrounding the slitted portion of the bore member and coacting means therebetween, said coacting means comprising a forwardly converging surface on the slitted member and a ring contacting surface on the outer cylindrical member to constrict the slitted portions when the outer cylindrical member moves rotatively and axially in the rearward direction, a swinging duct member having one end of its duct connected to the bore and its other end having a direction of discharge substantially in a plane normal to the axis of the bore, the outer rotatively movable cylindrical member having a plurality of spaced abutments providing gas-impinging surfaces in position to register with and receive impulses successively from the gas discharged from the duct to revolve the outer cylinder by increments as the gun is successively discharged.

2. An automatic choke for gun barrels comprising a bore member having a bore, means for securing the bore member to the barrel of a gun with the bore in axial alignment with the gun bore, the bore member having slits at the outer end of the bore, an outer cylindrical member having a gas-impinging surface and surrounding the slitted portion of the bore member and coacting means therebetween, said coacting means comprising a forwardly converging surface on the slitted members and a ring contacting surface on the outer cylindrical member to constrict the slitted portions when the outer cylindrical member moves rotatively and axially in the rearward direction, a swinging duct member having one end of its duct connected to the bore and its other end having a direction of discharge substantially in a plane normal to the axis of the bore and substantially tangential to the outer surface of the outer cylindrical member, the outer rotatively movable cylindrical member having a plurality of spaced ahutmcnts providing gas-impinging surfaces in position to register with and receive successive impulses 'from the gas discharged from the duct to revolve the outer cylinder by increments as the gun is discharged, and a spring beneath the discharge end of the duct member to absorb the recoil and return the discharge end of the duct member to its operative position.

3. An automatic choke as described in claim l, having a series of abutments for successively constricting the slitted member.

4. An automatic choke as described in claim l, the cylindrical member having a series of stops being successively operative to stop the rotation of the cylindrical member at points corresponding to the abutments.

References Cited in the tile of this patent UNITED STATES PATENTS 2,453,747 Egleson Nov. 16, 1948 2,589,738 Sedberry Mar. 18, 1952 2,663,961 White Dec. 29, 1953 

